1. Field of Invention
The present invention relates to a mounting case to accommodate an electro-optical device, such as a liquid crystal panel, which is used as a light valve of a projection display apparatus, such as a liquid crystal projector, an electro-optical device in the mounting case, in which the electro-optical device is accommodated or encased in the mounting case, and a projection display apparatus including the electro-optical device encased in the mounting case.
2. Description of Related Art
In the related art, generally, when a liquid crystal panel is used as a light valve of a liquid crystal projector, the liquid crystal panel is not provided in an exposed state on a console, etc., constituting the liquid crystal projector, but it is accommodated or encased in a suitable mounting case, and then the mounting case including the liquid crystal panel is provided on the console.
This is because the liquid crystal panel can be easily fixed and installed to the console by suitable screw holes provided in the mounting case.
In such a liquid crystal projector, source light emitted from a light source is projected on the liquid crystal panel in the mounting case as focused light. Light passed through the liquid crystal panel is enlarged and projected on the screen to display images. In this way, since enlarged projection is generally predetermined in such a liquid crystal projector, relatively intensive light emitted from a light source, such as a metal halide lamp is used.
However, in this construction, first, there is a problem in that the temperature of the liquid crystal panel encased in the mounting case rises. That is, the rise in temperature causes the rise in temperature of the liquid crystal interposed between a pair of transparent substrates in the liquid crystal panel. Therefore, the characteristics of the liquid crystal are deteriorated. In addition, when the light emitted from the source light is uneven, the liquid crystal panel is partially heated, and then the deviation of its transmittance is generated by the so-called hot spots. Thus, the quality of projected images deteriorates.
A technique for preventing the rise in temperature of the liquid crystal panel includes an approach for preventing the rise in temperature of the liquid crystal panel by providing a heat radiating sheet between a liquid crystal panel and a heat radiating plate in the liquid crystal display module including a case, which is referred as a “mounting case” in this specification, having the liquid crystal panel and the heat radiating plate for holding and accommodating the liquid crystal panel.
In addition, in order to address the problem, other approaches, such as an approach of providing a light shielding film on a substrate positioned at the side of the liquid crystal panel on which light is incident and an approach of forming the mounting case, in which the liquid crystal panel is held or accommodated, using a light reflective material, have been known.
However, the related art approaches to prevent the rise in temperature of the liquid crystal panel have the following problems. As long as intensive light is emitted from the light source, the problem of the rise in temperature of the liquid crystal panel may occur at any time. Therefore, in order to obtain still higher image quality, more effective measures to reduce or prevent the rise in temperature are required instead of or in addition to the aforementioned approaches.
For example, according to the approach of using the radiating sheet, the heat accumulated in the liquid crystal panel can be effectively radiated. However, assuming that the radiating sheet is provided to cover the entire surface of the substrate, the approach can be used for a reflective liquid crystal panel, but cannot be used for a transmissive liquid crystal panel.
In addition, according to the approach of reflecting light by the light shielding film and the mounting case, as the areas of the light shielding film and the mounting case increase, the amount of the reflected light increases. Thus, the rise in temperature of the liquid crystal panel can be surely reduced or prevented. However, if the amount of the reflected light increases indiscriminately, the stray light increases in the housing to accommodate the liquid crystal panel in the mounting case. Thus, the quality of images can be deteriorated. In addition, since the increase of the area of the light shielding film causes the reduction of the amount of the light from the source light, which is to be originally incident to and to pass through the liquid crystal panel, the image can be darkened. Thus, it is contrary to the aforementioned purpose in which the intensive light is used, in order to display a brighter image. Accordingly, the aforementioned related art approaches cannot be a total solution for the above problems.